Drill bit



Patented Mar. 19, 1940 UNITED STATES DRILL BIT George G. Harrington, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tea, at

. corporation of Texas Application July 19, 1937, Serial No. 154,421

6 Claims.

This invention relates to rotary drill bits for use in well drilling and the like, and has particular reference to the arrangement of bearings and supports for the roller cutters employed in such bits.

In the type of bits to which this invention relates roller cutters having cutting teeth formed thereon are rotatably mounted upon shafts fixed in the bit head. During the operation of the bit enormous radial loads are placed upon these cutters and a considerable end thrust is involved. In order that the bearings for supporting these roller cutters on their shafts may function properly, it is important that they be so placed that they will least likely be damaged or have their v life shortened due to excessive loads, or loads for which they are not intended, or due to the presence or ingress of foreign matter into the bearings. It is further necessary that the shafts upon which these cutters are supported shall be firmly and positively supported in the bit head.

In view of the foregoing, it is an object of this invention to provide for the mounting of roller cutters in a bit of this type in such a manner that the bearings and supports for said roller cutters will perform their functions with the greatest efliciency over a maximum period of time.

It is a more specific object to locate the thrust 30 bearings for such roller cutters in a position remote from the greatest radial load on such cutters.

It is a further object to so locate the thrust bearings with respect to the remaining parts of the device as to protect them in the greatest possible degree from contact with the drilling fluid and with the debris produced in the drilling operation.

Another object of this invention is to provide for the taking of the radial load upon the cutters by radial hearings in the greatest possible degree and to remove suchloadfrom the thrust bearings insofar as it is possible to do so.

Other objects and advantages will become apparent from the following description and claims taken in connection with the accompanying drawing, wherein like numerals indicate corresponding parts throughout.

In said drawing:

Fig. l is a vertical sectional view illustrating the lower portion of a bit embodying bearings and supports constructed in accordance with this invention.

. Fig. 2 is a similar view illustrating a modified form of roller cutter and showing the entire bit head, the upper portion of such head being illustrated in elevation.

Fig. 3 is a bottom plan view of the bit illustrated in Fig. 2.

The bit head illustrated in Fig. l and desig- 5 nated by the numeral I is provided with oppositely disposed downwardly extending ears or supports 2 and 3 adapted to receive and support the opposite ends of the shafts upon which certain of the cutters known as cross roller cutters 10 are to be mounted. A bridge 4 having a transverse opening therethrough and a small opening 5 extending upwardly from the bottom surface of the bridge onto the transverse opening, extends transversely of the bit head in a direc- 15 tion substantially at right angles to a line between the ears 2 and 3. Side cutters 6 are rotatably mounted upon inwardly inclined spindles carried by downwardly extending supports I, and the bridge 4 extends between the lower and inner :0 ends of said spindles. The upper end of the bit head is threaded at 8 in the customary manner to receive the drill collar on the lower end of the drill stem by which the bit is to be rotated.

The shaft which extends between the ears 2 25 and 3 is illustrated as being formed in two parts 9 and I0, respectively, these parts having their inner ends II disposed. within the opening through the bridge 4. Thus each part 9 and ID of this shaft is supported at its outer end by one of the ears 2 and 3, and at its inner end by the bridge 4.

The portion 9 of the transverse shaft is formed with a roller race I2, a shoulder I3 forming a ball thrust race, and a roller race It of larger 35 diameter than the race I 2, said races being adapted to receive, respectively, the radial roller bearing I5, the thrust ball bearing I6, and the radial roller bearing I1. Rotatably mounted upon the radial roller bearing I2 is a cutter 40 section I8, and rotatably mounted upon the thrust ball bearing I6 and the radial roller bearing I! is a second cutter section I9. The cutter section I8 is provided with an overhanging part 20 which cooperates with the inner end portion 45 of the cutter section I9 so that the two sections will be positively related to each other at all times. The cutter section I9 is prevented from moving outwardly in an endwise direction by means of the ball thrust bearing I6. The inner 50 cutter section I8 is prevented from outward endwise movement by contact with the inner end of the cutter section I9. A plate or washer M is placed about the outer end of the shaft 9 between the end of the cutter section I9 and the 55 car 2 for the purpose of protecting the outer end of the cutter during the operation of securing the outer end of the shaft 9 in place as will be presently set forth.

The cutter shaft section I is provided with an inner radial bearing race 22, an intermediate thrust bearing race 23, and an outer radial hearing race 24, these races being adapted to receive respectively the roller radial bearing 25, the ball thrust bearing 26, and the. roller radial bearing 21. The cutter 28 is provided with inner races adapted to receive the said two radial bearings and the intermediate thrust bearing, respectively. The plate 29 surrounds the outer end portion of the shaft section ID in a manner similar to that previously described in connection with the plate 2|.

In assembling the parts just described, the cutters and the radial and thrust bearings are first placed upon the respective shaft sections, and the inner ends of these sections are placed in the opening through the bridge 4. The outer ends are then positioned within the slotted or lower ends of the ears 2 and 3, respectively, and are secured in position by welding over the same as illustrated by the niuneral 30. The inner or adjacent ends of these shaft sections are secured in place and joined to each other by means of welding through the opening to provide a key 3i of weld metal. The shaft sections are thus positively secured to their supports at their opposite and adjacent ends.

Referring to Fig. 2, a slightly modified form of structure is illustrated in which one of the shaft sections 32 is provided with an inner radial bearing race 33, an intermediate thrust bearing race 34, and an outer radial bearing race 35, which races are adapted to receive, respectively, the inner radial roller bearing 35, the intermediate ball thrust bearing 31, and the outer radial roller bearing 38. The cutter 39 is provided with corresponding races on its inner surface, and is supported upon the shaft section 32 in much the same manner that the cutter 28 is supported upon the shaft section In in Fig. 1.

The shaft section 40 of Fig. 2 is not provided with an inner radial bearing race, but is provided only with a thrust bearing race 4| and an outer radial bearing race 42 located radially outwardly from the thrust bearing race. These races receive, respectively, the ball thrust bearing 43 and the radial roller bearing 44. The cutter 45 is of much the same type as thecutter 39, except that it is provided with no inner radial bearing race. Plates 46 and 41 are placed about the outer ends of the shaft sections 32 and 40 in the same manner that the plates 2| and 29 are placed about the outer ends of the shaft sections 9 and ID in Fig. 1.

In connection with both of the modifications above described, it will be noted that the thrust bearing has been very carefully located so as to position it at a point remote from the zone of application of the greatest radial load upon the cutters. The thrust bearing is adapted simply to take up the tendency of the cutter to move outwardly during the operation of the bit. It is desired that the thrust bearing take as little of the radial load as possible in order that it might not become unduly worn or damaged by the heavy radial load such as is ordinarily encountered by tools of this type.

It is to be noted that in Fig. 1 the ball thrust bearings are in each instance placed remote from the outer ends of the cutters in which location occurs the greatest radial load during operation. Also, the thrust bearings have in each instance in Fig. 1 been placed between two radial bearings so that substantially the entire radial load will be taken on both sides of the thrust bearing by a radial bearing especially adapted to take this form of load. At the same time, the ball thrust bearing has been located at a position remote from the ends of the cutters so that it will be least likely to become impregnated and caked with drilling fluid and debris contained therein.

It will thus be seen that means has been provided for carrying out all of the objects of this invention in a thoroughly practical and efficient manner.

Having described my invention, I claim:

1. A drill bit comprising a head, side and cross roller cutters carried by said head, a divided shaft for supporting said cross roller cutters, a pair of ears extending downwardly from said head and supporting the outer ends of said divided shaft, 2. bridge extending between said side roller cutters and supporting the inner ends of said divided shaft, weld material securing the outer ends of said divided shaft to said ears and the inner ends thereof to said bridge and to each other, radial roller bearings between the sections of said divided shaft and said cross roller cutters, respectively, said radial bearings being located adjacent the ends of said cross roller cutters, and a ball thrust bearing between the sections of said divided shaft and said cross roller cutters, respectively, intermediate the ends of said cutters, the inner of said radial bearings being of smaller diameter than the outer of said radial roller bearings.

2. A drill bit comprising a head, side and cross roller cutters carried by said head, a divided shaft for supporting said cross roller cutters, a pair of ears extending downwardly from said head and supporting the outer ends of said divided shaft, a bridge extending between said side roller cutters and supporting the inner ends of said divided shaft, radial roller bearings between the sections of said divided shaft and each of said cross roller cutters adjacent the outer end thereof, and a ball thrust bearing between the sections of said divided shaft and each of said cross roller cutters, respectively, remote from the outer ends of said cutters.

3. A drill bit comprising a head, side and cross roller cutters carried by said head, a divided shaft on said head for supporting said cross roller cutte'rs, radial roller bearings between the sections of said divided shaft and said cross roller cutters, respectively, said radial bearings being located adjacent the ends of said cross roller cutters, and a ball thrust bearing between the sections of said divided shaft and said cross roller cutters, respectively, intermediate the ends of said cutters, the inner of said radial bearings being of smaller diameter than the outer of said radial roller bearings.

4. A drill bit comprising a head, side and cross roller cutters carried by said head, a divided shaft on said head for supporting said cross roller cutters, radial roller bearings between the sections of said divided shaft and said cross roller cutters, respectively, said radial bearings being located adjacent the ends of said cross roller cutters, the inner of said radial bearings being of smaller diameter than the outer of said radial roller bearings.

5. A drill bit comprising a head, side and cross roller cutters carried by said head, a divided shaft on said head for supporting said cross roller cutters, radial roller bearings between the sections of said divided shaft and each of said cross roller cutters adjacent the outer end thereof. and a ball thrust bearing between the sections of said divided shaft and each of said cross roller cutters, respectively, remote from the outer ends of said cutters 6. A cross roller shaft for a cross roller bit, said shaft comprising two sections adapted to be joined together at their inner ends in use, each of said sections having radial and thrust bearin races, and the adjacent ends of the bearing portions of said sections being of smaller diameter than the outer ends thereof.

' GEORGE G. HARRINGTON. 

